Bulk Perovskite Crystal Properties Determined by Heterogeneous Nucleation and Growth.

In metal halide perovskites, charge transport in the bulk of the films is influenced by trapping and release and nonradiative recombination at ionic and crystal defects. Thus, mitigating the formation of defects during the synthesis process of perovskites from precursors is required for better device performance. An in-depth understanding of the nucleation and growth mechanisms of perovskite layers is crucial for the successful solution processing of organic-inorganic perovskite thin films for optoelectronic applications. In particular, heterogeneous nucleation, which occurs at the interface, must be understood in detail, as it has an effect on the bulk properties of perovskites. This review presents a detailed discussion on the controlled nucleation and growth kinetics of interfacial perovskite crystal growth. Heterogeneous nucleation kinetics can be controlled by modifying the perovskite solution and the interfacial properties of perovskites adjacent to the underlaying layer and to the air interface. As factors influencing the nucleation kinetics, the effects of surface energy, interfacial engineering, polymer additives, solution concentration, antisolvents, and temperature are discussed. The importance of the nucleation and crystal growth of single-crystal, nanocrystal, and quasi-two-dimensional perovskites is also discussed with respect to the crystallographic orientation.

Microwave-facilitated crystal growth of defect-passivated triple-cation metal halide perovskites toward efficient solar cells.

Structural defects at the surface and within the bulk of perovskite films hinder efficient energy conversion in solar cells due to the loss of charge carriers through non-radiative recombination. Post-passivation approaches have been proposed in an attempt to eliminate surface defects, with bulk defects being rarely studied. Moreover, it is of interest to investigate the difference in the perovskite crystal growth with and without simultaneous defect passivation. Here, we study a new crystal growth strategy to realize high-quality triple-cation perovskite crystals via utilizing microwave irradiation combined with a continuous supply of defect passivators from a reservoir solution of trioctyl-n-phosphine oxide (TOPO). The proposed method facilitates the growth of perovskite crystals with TOPO ligand coordination in the whole film region. Consequently, the processed perovskite film demonstrates distinctive features of significantly suppressed non-radiative recombination, substantial defect reduction and morphological changes compared to the perovskites processed by conventional thermal annealing. The power conversion efficiency is enhanced owing to the improved open-circuit voltage (Voc) and short-circuit current (Jsc). The results of this study are expected to assist in the development of diverse approaches for the control of perovskite crystal growth with in situ defect passivation toward high efficiency in solar cells.

Synthesis of biodiesel from chicken skin waste: an economic and environmental biofuel feedstock in Bangladesh.

One of the dominating meat supply industries, the poultry chicken sector, is facing waste management concerns worldwide. Due to high oil content containment, biofuel researchers emphasized poultry waste as abundant, cheap, and high-quality feedstock for biodiesel production. Therefore, in the current study, an experimental investigation of biodiesel production from wasted chicken skin through the transesterification process has been performed. The chicken skin used in this study for biodiesel production can be used as the potential waste source for biodiesel production worldwide. Techno-economic, environmental, and sustainability analyses were also performed. During the synthesis, the reaction was conducted with potassium hydroxide (KOH), and the process yielded 48% biodiesel. The cost of electricity for providing electricity is estimated at US$0.575 per kWh when an auto-sized generator has been fueled by biodiesel. The environmental and substantiality analysis found that biodiesel is more suitable than conventional diesel as an environmentally friendly and sustainable fuel.

Detection of mold on the food surface using YOLOv5.

The study aimed to identify different molds that grow on various food surfaces. As a result, we conducted a case study for the detection of mold on food surfaces based on the "you only look once (YOLO) v5" principle. In this context, a dataset of 2050 food images with mold growing on their surfaces was created. Images were obtained from our own laboratory (850 images) as well as from the internet (1200 images). The dataset was trained using the pre-trained YOLOv5 algorithm. A laboratory test was also performed to confirm that the grown organisms were mold. In comparison to YOLOv3 and YOLOv4, this current YOLOv5 model had better precision, recall, and average precision (AP), which were 98.10%, 100%, and 99.60%, respectively. The YOLOv5 algorithm was used for the first time in this study to detect mold on food surfaces. In conclusion, the proposed model successfully recognizes any kind of mold present on the food surface. Using YOLOv5, we are currently conducting research to identify the specific species of the detected mold.